Generation And Detection Of Terahertz Wave Using A Parametric Process In Lithium Niobate

Terahertz wave with many unique properties has significant scientific research values and wide applications in the field of imaging, non-destructive testing, environmental monitoring, communication, security and so on. Recently, Generation and detection terahertz wave using a parametric process in lithium niobate has attracted more and more attention due to its advantages such as narrow linewidth, continously tunable, room temperature operation, compact structure, etc. Based on the stimulated Raman scattering of polariton in lithium niobate, in this thesis, we focus on terahertz wave radiation source, narrow linewidth terahertz wavelength meter, threshold pump of terahertz wave radiation source, and the theories and experiments of terahertz wave detection. The detailed research contents can be found as follows.(1) We derive the coupled-wave equations that describing the stimulated polariton scattering in a crystal.(2) We experimentally investigate two different coupling methods, which are silicon prisms coupler TPO and surface emitted TPO. The main factors which limit the frequency tuning range are discussed. Moreover, the impacts of the photorefractive effect in lithium niobate on the terahertz wave output are quantitatively studied. For surface emitted TPO, terahertz wave output efficiencies and frequency tuning ranges of three different configurations are measured.(3) A terahertz wavelength meter for direct wavelength measurements of narrow linewidth terahertz wave is designed and fabricated.(3) We theoretically and experimentally study the threshold pump of a typical TPO. The losses of the TPO are discussed. Moreover, we also provide some effective methods to lower the pump threshold.(4) We have established the steady-state theoretical model for detection of terahertz wave using a parametric process in lithium niobate, and obtained its analytical expression. To test the established model, numerical calculation method is employed. The frequency response characteristics and temperature effects of the detector are analyzed by using the steady-state theoretical model. We also establish the time-dependent theoretical model to explain the practical situation. The effects of various factors on the detection sensitivities are discussed.(5) We construct the system consisted of both terahertz wave generation and detection using a parametric process. The main system noise sources are analyzed and discussed. We have measured the signal-to-noise of terahertz wave detection with the parametric process method with and without a resonator, Golay cell and pyroelectric detector.